1. Field of the Invention
The present invention relates generally to a channel allocating apparatus and method in a communication system, and in particular, to a channel allocating apparatus and method in a wireless communication system.
2. Description of the Related Art
One of the major wireless communication system is the mobile communication system. The mobile communication system is configured to mainly provide voice communication service to users irrespective of their locations. It has been developed to additionally provide data services as well as voice services. The development of the mobile communication technology is a driving force behind the commercialization of the wireless local area network (WLAN) systems, the wireless local loop (WLL) systems, etc.
The above systems provide wireless communication services. Because radio resources are extremely limited, the efficiency utilized in allocating the radio resources must be increased to increase the system throughput. In this context, alot of time and energy is being expended toward the channel allocation in the systems. Among them, CDMA (Code Division Multiple Access) 1xEV-DO (Evolution-Data Only) is a system that allocates channels one of the more efficient manners. In the CDMA 1xEV-DO system, mobile stations (MSs) measure the strengths of pilot channels received from a base station (BS) and feed back the pilot signal strengths to the BS. The BS then allocates a forward channel to an MS in the best condition at a particular point in time and transmits the data to the MS. That is, the BS selects the MS in the best channel status based on the pilot strengths received from the MSs. Then, the BS allocates all of the channel resources to the MSs, being with the MS having the best channel status, at the next transmission time and transmits data to the MSs.
One problem in the channel allocation of the CDMA 1xEV-DO system is fairness in resource allocation. If a particular MS continuously has the best channel status and the other MSs have bad channel status, the latter are continuously excluded from the channel allocation. Yet, if channels are allocated to the other MSs having bad channel status, system throughput is decreased.
The wireless communication systems recently deployed include the CDMA and the TDMA (Time Division Multiple Access) systems. The CDMA and TDMA systems have inherent limits to increasing the throughput. Thus, studies are under way on methods of increasing throughput, aside from the methods currently in use in those systems. One of the methods is the OFDMA (Orthogonal Frequency Division Multiple Access).
In the OFDMA, orthogonal frequencies are allocated to MSs, for radio communication. However, there is no criteria for the allocation of the orthogonal frequency resources that has been specified so far. The channel allocation schemes adopted for the existing systems cannot be simply applied. Moreover, the existing schemes have the shortcomings of decreased throughput or unfairness. Accordingly, there is a need for a channel allocation method viable for the OFDMA system. At the same time, a method of determining an optimum hopping pattern or increasing the system throughput must be explored for an OFDMA system using frequency hopping.